In the past various types of marking machines have been employed for marking on work pieces such as metal or plastic tags of one nature or another. Such marking machines of the kind concerned in this invention have printing characters on the periphery of the marking wheel and are driven by a drive shaft to rotate the printing or marking wheel to a position where the selected printing character is directly superimposed over the work piece at which time the wheel or the work piece are caused to contact one another to effect the marking operation. Such marking machines are exemplified in my U.S. Pat. Nos. 4,322,173; 4,229,111 and 3,785,470.
Problems have been presented in such machines for adjusting the relative rotational position of the selected printing characters with respect to the work piece. Since the printing wheel is conventionally fixed to the drive shaft rotational alignment has been difficult. Such alignment to effect proper adjustment requires only a few degrees in relative rotation but can necessitate time consuming and complex adjustment.
A further problem has involved difficulty in removing the printing wheel to effect repair from time to time and in the past has involved the use of tool and considerable down time in the change-over operation.